Dynalyzer – Digital Display/Printer
OPERATION MANUAL
13
Figure 7:
Effect of 50% Trigger Level on Exposure Time
Single-phase generators should produce time values that are multiples of 1/120 of a second (8.33
milliseconds). Some generators start up with a small pulse phased 20° (approximately) ahead of
zero crossing. This voltage will, in many cases, be enough to begin the timing cycle. The deviation
in total exposure time from a fixed number of cycles may represent this time, unless of course the
exposure termination is not obtained at zero crossing. This effect will be most noticeable in short
exposures such as 1/120 and 1/60 second.
Figure 8:
Single-Phase Generator Exposure Time Measurement
The proposed convention for timing measurements of three-phase equipment is to measure the
voltage pulse width from intersection with 75% of the peak voltage. Some manufacturers use other
values in the calibration of their equipment. The LEVEL control must be set to that value.
TRIGGER
READ
TIME
1/60 SEC.
50% level= 2.7 ms. error
ERROR AREA
50% TRIGGER LEVEL
MEASURED
READ TIME
